Near-Field EMI Survey Kit for Industry 9kHZ to 6GHz
Near-Field EMI Survey Kit for Industry 9kHZ to 6GHz
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This high-fidelity and flexible Near-Field EMI Survey Kit is the essential companion for Spectrum Analysers and Oscilloscopes to measure the voltage and magnetic fields which characterise Electro-Magnetic Interference (EMI). The kit comes complete with near-field probes and connectivity adaptors. We recommend also purchasing a good current probe for direct measurement of conducted EMI current and common mode (leakage) current.
Near-field EMI probes are the 'sensor' to enable a technician measure noise, trace it back and physically locate the source of EMI, evaluate the impact of remedial steps, and finally document the efficacy of remedial work done.
Voltage E-Field vs. Current H-Field: Operational Context
Understanding which probe to use is critical for accurate troubleshooting:
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H-Field (Magnetic) Probes: These are sensitive to the magnetic field produce by the high-frequency current flow from conducted EMI. Use an H-Field probe to track noise traveling through traces, wires, and ground straps.
Regardless of whether conducted EMI currents arise from direct connection, capacitive coupling, or inductive coupling; the magnetic field which results from the current flow will be measurable using an H-Field EMI probe.
High-frequency power electronics are the common root cause of these currents (e.g., VSD switching transients), though partial discharge and arcing is another probable cause.
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E-Field (Electric) Probes: These are sensitive to voltage potential. Use these to find high-impedance noise sources, such as ungrounded heat sinks or floating traces that are acting as antennas. E-Field is also preferred for measuring deliberate sources of electromagnetic radiation which relate to communication technologies (WiFi, AM/FM radio, portable radios etc).
Kit Contents
- 7x EMI Near-Field Probes for measurement from 9 kHz to 6 GHz.
- 1x 1.5m SMA Lead
- 6 pcs RF Adaptor Kit
- 1x BNC male to 4mm banana female insulated adaptor
- 1x BNC female to 4mm banana male insulated adaptor
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1x Extra Large Type III H-Field: Features a 45mm loop designed for low-frequency CS rectification experiments and large-cable EMI monitoring. Note: Ensure probe is appropriately insulated if used near high-voltage exposed conductors.
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1x Vertical H-Field Probe: The coil is set at 90° to the shaft. This allows the probe to be inserted vertically between large components (like capacitors or inductors) on a PCB to "touch" the noise source directly. (1 MHz – 3 GHz)
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3x Standard H-Field probes: 6mm, 10mm, and 20mm loop H-field probes (1 MHz – 6 GHz)
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1x The Compound E+H Field Probe: The "Combined" probe (1 MHz – 6 GHz) allows for rapid "sniffing" without distinguishing the source type—ideal for the initial walkthrough of a noisy plant floor.
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1x E-Field Probe:
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1x 1.5m SMA Lead:
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6 pcs RF Adaptor Kit:
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Insulated Banana Adaptors
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Deep Dive: Extra-Large Shielded H-Field Probe for 9kHz to 90MHz
Of special mention for industrial EMI investigation, this kit includes the Type III H-Field Probe. In our experience, we find surveying the H-field in the range of 10kHz to 10MHz is the most relevant to identifying and resolving EMI in industry.
- 4-Layer PCB Structure: This Type III probes features a fully shielded, symmetrical 4-layer design.
- Common-Mode Rejection: The symmetrical structure greatly inhibits electromagnetic interference from the external environment, ensuring that the signal you see on your HSA is purely representative of the local magnetic field under investigation.
- Linearity & Stability: Features a highly linear response from 9 kHz to 90 MHz, making it the primary tool for quantifying EMI current flow.
Frequency Spectrum & Industrial EMI
The different probes in this kit correspond to the stages of EMI development in high-power electronics. Issues which exist at lower frequencies give rise to EMI emissions at higher frequencies.
In our experience, we've found that surveying the H-field in the range of 10kHz to 10MHz is the most relevant to identifying and resolving EMI in industry.
| EMI Category | Frequency Range | Industrial Relevance & Measurement |
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| Harmonics | 50 Hz to 2.5 kHz |
Power quality, transformer saturation, heating. EMI probes are not effective at frequencies this low. To measure in this frequency range, use a current probe such as the Owon CP024 or the Owon CMS clamping scope meter. |
| Supraharmonics | 2 kHz to 150 kHz |
VSD switching noise, PLC communication interference. From 9kHz, you can measure the magnetic fields arising from current flow using the Large H-Field probe. |
| Conducted EMI | 150 kHz to 30 MHz |
Noise traveling through mains cabling and ground loops. In this range you can survey using a range of different probes and can alternate between H and E field depending on what you're trying to measure. Larger probes are better for area-of-effect and smaller ones have better spatial resolution - allowing you to pinpoint emitters. |
| Radiated EMI | 30 MHz to 6 GHz | Wireless network disruption, sensor signal corruption. |
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